Errrrmmmmm well my 325d is only meant to do 47mpg combined, but yesterday at 2 degrees Celsius I drove a 380 mile return trip to Birmingham at 75mph and it returned 54.3mpg, plus I was squeezing the throttle hard on slip roads etc.

So you should be comparing to extra urban then which is around 60mpg.

54MPG is a great figure at that speed, but I stand by what I said, barely any cars hit the EU mpg ratings in the real world.